This invention is generally directed to resin compositions useful for incorporation into toner and developer compositions. More specifically, the present invention relates to polysiloxanes resins, especially branched or grafted polysiloxane styrene ternary polymers useful for the formulation of toner compositions that can be selected for imaging processes wherein silicone release oils are avoided or contained in the toner composition. In one embodiment, there are provided in accordance with the present invention branched polysiloxane styrene/butadiene polymer resins that can be selected for the formulation of toner compositions containing therein pigment particles, and optional additive particles. In addition, the present invention is directed to processes for the preparation of the aforementioned resins by suspension free radical polymerization processes with short reaction times, and wherein products of high purity and high yields are obtained. Processes for the preparation of the aforementioned copolymers using free radical procedures can be accomplished by the emulsion polymerization techniques as illustrated in U.S. Pat. No. 4,469,770; and suspension polymerization processes as illustrated in U.S. Pat. No. 4,558,108, the disclosures of each of these patents being totally incorporaed herein by reference. The toner and developer compositions formulated with the polysiloxane resins illustrated herein are particularly useful in electrophotographic imaging methods with soft roll fusers, and wherein release agents such as silicone oils selected to prevent toner particles from adhering to the surface of the fuser, are not needed, or are incorporated into the branched or grafted polysiloxane resins illustrated herein.
Toner and developer compositions, especially those containing charge enhancing additives, are well known, reference for example U.S. Pat. Nos. 3,893,935; 3,944,493; 4,007,293; 4,079,014 and 4,394,430. Thus, for example, there is described in U.S. Pat. No. 3,893,935 the use of certain quaternary ammonium salts as charge control agents for electrostatic toner compositions. Further, there is disclosed in U.S. Pat. No. 4,338,390 developer and toner compositions having incorporated therein as charge enhancing additives organic sulfate and sulfonate substances. A similar disclosure is present in U.S. Pat. No. 4,394,430. Moreover, there are disclosed in U.S. Pat. No. 4,298,672, the disclosure of which is totally incorporated herein by reference, positively charged toner compositions with resin particles, and pigment particles; and as a charge enhancing additive, alkyl pyridinium compounds, inclusive of cetyl pyridinium chloride.
Additionally, toner and developer compositions useful in xerographic imaging processes wherein silicone oils are not needed are known, reference for example U.S. Pat. No. 4,556,624, the disclosure of which is totally incorporated herein by reference. In this patent, there are disclosed improved positively charged toner compositions comprised of a polyblend mixture of crosslinked copolymer compositions, a second polymer, pigment particles, and a particular wax component thereby enabling the toner compositions to be selected for imaging systems wherein release fluids are not required. The types of resin described in this patent and other patents relating to toner compositions, including those compositions useful in imaging methods wherein release fluids are avoided include polyamides, epoxies, diolefins, polyurethanes, vinyl resins and polymeric esterification products of a dicarboxylic acid, and a diol comprising a diphenol. Typical monomers selected for the preparation of the appropriate aforementioned resins include styrene, p-chlorostyrene, unsaturated mono-olefins such as ethylene, propylene, butylene, isobutylene and the like; vinyl esters such as esters of monocarboxylic acids including methyl acrylate, ethyl acrylate, n-butylacrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methylalpha-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and other similar acrylates; acrylonitrile, methacrylonitrile, and acrylimide; vinyl ethers such as vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether, and the like; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopropenyl ketone, and N-vinyl indole, N-vinyl pyrrolidene, and the like; styrene butadiene copolymers, and mixtures thereof.
As preferred toner resins illustrated in the U.S. Pat. No. 4,556,624, there can be selected styrene polymers, and the esterification products of a dicarboxylic acid, and a diol comprising a diphenol. The aforementioned polyesters are illustrated in U.S. Pat. No. 3,590,000, the disclosure of which is totally incorporated herein by reference. Other specific preferred toner resins include styrene/methacrylate copolymers; styrene/butadiene copolymers; polyester resins obtained from the reaction of bisphenol A and propylene oxide; followed by the reaction of the resulting product with fumaric acid; branched polyester resins resulting from the reaction of dimethylterephthalate, 1,3-butanediol, 1,2-propanediol, and pentaerythritol; styrene butadiene copolymers prepared by a suspension polymerization process, reference U.S. Pat. No. 4,558,108, the disclosure of which is totally incorporated herein by reference; styrene butadiene resins prepared by an emulsion polymerization process, reference U.S. Pat. No. 4,469,770, the disclosure of which is totally incorporated herein by reference; and Pliolites.
Furthermore, illustrated in U.S. Pat. No. 3,418,354 are processes for obtaining olefin-polyoxyalkylene copolymers by a graft reaction with a peroxide, whereby there are generated free radical sites on the backbone polymer. One process embodiment disclosed in the U.S. Pat. No. 3,418,354 involves the addition of an alpha olefin, such as styrene, and a peroxide to a polyoxyalkylene compound, such as a siloxane, wherein there results a graft copolymer; and more specifically, an olefin-polyoxyalkylene graft copolymer, see column 2, line 23. In Japanese Patent Publication No. 46-9355, there is disclosed a process for the preparation of graft block copolymers with a polysiloxane chain by the reaction of a functional polysiloxane with a polymer obtained from the anion polymerization of a styrene or a butadiene. Japanese Patent Publication No. 58-225103 discloses a method for the crosslinking of a thermoplastic resin by the reaction of a hydrogenated styrene-butadiene-styrene block copolymer with a silane in the presence of organic peroxides. Further, in U.S. Pat. No. 3,691,257 there are disclosed organic polymers modified by incorporating therein a siloxane polymer organic block copolymer; while Japanese Patent Publication No. 57-187345 describes a rubber modified styrene resin prepared by continuous bulk polymerizations in the presence of organic polysiloxanes and 1,2-vinyl polymers.
However, there is a need for new toner resins that possess desirable characteristics, and that are useful in electrophotographic imaging systems wherein, for example, release oils are avoided. Additionally, there is a need for simple economical processes that enable the preparation of polysiloxane resins in high yields exceeding 80 percent, for example; and wherein the resulting products are of an acceptable purity exceeding in some instances 90 percent. There is also a need for novel toner resins which are useful as toner compositions when selected for the development of images, and wherein fixing is accomplished without the need for release fluids. In addition, there is a need for resins useful for the formulation of toner compositions that possess desirable mechanical properties, excellent fusing characteristics, and acceptable release properties. Moreover, there is a need for developer compositions containing therein toner components, including the polysiloxanes illustrated herein, and carrier components. There is also a need for imaging and printing methods wherein there are selected toner and developer compositions containing therein the polysiloxanes disclosed herein, and wherein release fluids, such as silicone oils, are avoided during the fusing process. Moreover, there remains a need for improved toner compositions that are compatible with fusing rolls incorporated into imaging apparatuses, especially Viton fuser rolls.
With further respect to the invention of the present application, particularly the developer compositions thereof, one Viton soft fuser roll selected for use in electrophotographic copying machines is comprised of a soft roll fabricated from lead oxide and DuPont Viton E-430 resin, a vinylidene fluoride hexafluoropropylene copolymer. This roll contains approximately 15 parts of lead oxide and 100 parts of Viton E-430, which mixture is blended and cured on the roll substrate at elevated temperatures. Apparently, the function of the lead oxide is to control the generation of unsaturation by dehydrofluorination which can cause crosslinking, and to provide release mechanisms for the toner composition.